Distributer-arm.



'.l. F. CAVNAGH.

DISTBIBUTER ARM;l APPL'lcAUaN FILED JUNE Il. 1917.

Patented Deo. 4, 1917.

UNITED sTATEs PATENT oEEroE.

.TIN F. CAVANAGH, 0F MERIDEN, CONNECTICUT, A-SSIGNOR TO THE CDNNEGTIGUTTELEPHONE 6b ELECTRIG'CMPANY, 0F MERIDEN,

CNNECTICUT, A CORPORATION DISTRIBUTER-ARM.

'imi-48,612.

Specification of Letters Patent.

Patented nee. 4, 1917.

Application led June l, 1517. Serial No. 174,114.

'tot mz't'may concern.' v it known that I, JOHN F.k CAVANAGH,

rtizenof the United States of Ame1-ica, ding at Meriden, Conn., have.invented anew and useful Distributer-Arm, of which Ai samel time simpleand practical connection between the distributer arinf and the uter.shaft.

f Accordingly, my invention consistsin part, in constructing .thedistributer arm, which is usually molded in suitable-l insudistriblatingmaterial, with a' hore'to tit over the `distribut'er shaftps'aid borehaving. radial.

projections at separated 'points therein to,-

engagethe shaft and portions between said bearing projections recessedaway from the shaft.4 A further feature is the provision of oppositelydisposed driveshoulders within the bore separated from each other' anddisposed to engage a .driving tang on the end of the distributershaft.

Other features and details of construction will become apparent as thespecification proceeds,

in the accompanying drawing I have illustrated my invention asembodied,- in practical and at present preferred forms, but l wouldha've it understood that changes and modifications may be made withoutdespirit and scopeof the invention.

ln this drawing Figure 1 is a broken .sectional view of an ignitiondistributor having my invention incorporated therein.

Fig. 2 is a bottom plan view of the distributer arm as detached `fromthe upper end of the distributor shaft, shown also in top plane in thisview, illustrating in dotted lines the position of the distributor shaftwithin the bore of the arm.

Fig. 3 is a bottomplan view of the arm ina slightly modified form.

Referring particularly to Fig. 1, 5 designates the distributor shaftdriven from the engineA by suitable gearing and constructed intheillustration, as customary, with one side of the upper end portionthereof out away to (provide a. driving tang 6. This upper 611 dil'erentsides of said bore portion of the shaft is usually substantiallycylindrical as illustrated to receive the hub of the distributer arm.

The distributer arm 7, is usually molded to shape in suitable insulatingmaterial and in general is'formed with a hub portion 8, fitting over theshaft andan outstanding arm 9, carrying a distributor contact 10, ,theend of this contact in the rotary lnovement -of the armcoming intooperative relation y wlth sultable relatively stationary contacts -l1,and current being supplied to the'rotary contact by. a spring brush 12,which bears against a current conducting point 13.

The details of the connection between the shaft and distributor arm willperhaps be `best understood by reference to Fig. 2, wherein it will beseen that the hub portion of the arm is formed with a lgenerallycylindrical bore 14 to receive the end of the shaft and inwardlyprojecting radial extensions 15 at for engagement with the walls of theshaft.. In practice, the bore is made slightly larger than the diameterof the shaft and the bearing projections 15 project radially inward justfar enough to engage with and center the arm upon the shaft. Thiscondition is illustrated by the dotted lines in Fig. 2, which show howthe radial projections bear upon the shaft and the portions between saidbearing projections are recessed away from the shaft.` The result ofthis 'construction is that the distributer arm is accurately centeredupon the shaft, irrespective of slight irregularities in the moldingoperations and in spite of certain shrinkages which are likely to occurin molded articles of this character. j

The arm is keyed upon the shaft land caused to rotate therewith'byproviding it, in this invention, with drive shoulders 16, projectinginwardly into the .bore at opposite'sides thereof and terminating inabrupt shoulders 17 to engage the driving face of the tang 6, thesedrive shoulders being disconnected fromeach other as shown in Fig. 2,vso as to engage the tang at separated points. By means of thisconstruction, the bore is substantially symmetrical, so that anyshrinkage which may occur will be more or less regular and will notdistort the shape of the bore. lThis construction furthermore provides arm driving engagement at'twq relatively widely separated points` betweenthe driving tang and the arm, causing the arm to move positivelytherewith. r. l

In the form shown in these first two figures, the distributer armcontacts with the shaft in but four places. Friction is thereforereduced to a minimum, enabling the arm being readily placed upon andremoved from the shaft. Also, it will be seen that if the stock'shouldshrink to a point which would be prohibitive in the old style arm, whichis made to contact with the shaft at all points circumferentially, aslight effort merely is required to slip the distributer arm over theend of the shaft, the shaft in somecases having a broachiiig effect onthe projections of the bore as the arm is forced in place thereover.Vith my new construction furthermore, any slight distortion from thecircular has no ill effect upon the mounting of the -arm on thedistributer shaft.

The number and shape of the bearing projections may be varied. Forinstance, as shown in Fig. 3 there mayl be only three bearingprojections disposed equidistantly about the bore, this providing thethreepoint support, desirable in mechanisms. The projections inthis-case also are shown more in the nature of ribs, as distinguishedfrom the rather flat style of projections shown .in thefrst form;

Another feature of my invention which is of considerable practicalimportance from a manufacturing standpoint is that the` core or'pinwhich is used to mold the bore in the distributer armnia be made as asolid pin, except for the s ight depressions in the sides thereof,necessary to form the ribs l or bearing projections, and the relativelysmall pockets in the end thereof necessary to form the two separateddrive shoulders. This practically solid construction of the pin allowsfor the pin beingk hardened as much as necessary for practical moldingpurposes without the danger of breaking the pin, due to fragility of anyof its parts. This feature will be fully appreciated when it is realized-that this pin or core used in forming the bore should be made quitehard to resist the abrasive action of the molding material and when itis understood further that it has been impractical heretofore to makethe pin as hard as desirable because when so made, the rojection or tangon the i end of the pin ha in the mold.

The advantages of the invention will be more fully appreciated when itis realized a tendency to break off that heretofore there has alwaysbeen considerable waste in moldin articles of this character, because ofthe yrgact that the concentric or circular seat in the distributer armhad to be molded very close to size so as to accurately 'fit thedistributer shaft, and that even a relatively slight4 shrinka "ordistortion would make 4these close members unfit for use. As there ispractically always some shrinkage in these articles, it can beunderstood that the percentage of unusable products was relatively high.The present invention makes it possible to mold the ribbed portions ofthe bore in the distributer arm accurately to size and then, even thoughsome shrinkage does take place, said distributer arms may still be usedby simply forcing the arm ove'theend of the distributer shaft, the shaftacting in such cases, as above indicated, in a breaching capacity tomill off the high points on the ribs, producing an accurate andclosefitting ,engagement between the shaft and distributer arm.

What I claim is 1. In combination with a distributer shaft having theend portion cut away at one side thereof to providev a driving tang anda distributer arm of insulatin a shaft-receiving. bore to t the endportion of the shaft, and separated drive shoulders projecting intoopposite side portions of said bore to engage the driving tang atseparated points thereon.

2. .As an article of manufacture, a disi tributer arm of insulatingmaterial arranged to bemountedon a shaft of an igniter mechanism, saidVarm having a bore approximately tting the end of said shaft, inwardprojections on the walls of said bore arranged to be partially cut-awayby the shaft upon the application of said arm thereto whereby a. snugfit may be obtained between said parts. u

3. As an article of manufacture, a distributer arm of insulatingmaterial -arranged to be mounted on a shaft of an ignter mechanism, saidarm having a bore approximately fitting the endv of said shaft, inwardprojections on the walls of said bore arranged to be partially cut-awayby the shaft upon the application of said arm thereto whereby a snu fitmay be obtained between said parts, sai inward projections being in theform oflongitudnally arranged spaced ribs.

JH-N F. CAVANAGH.

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